“Why ship Soriel when Asriel exists” because it’s canon that Toriel is incredibly unhappy with Asgore’s habit of /killing children she cares about and taking their souls/ and divorced him and still isn’t on good terms with him
Alphys even asks if you think toriel and asgore will get together and if you say you don’t think they will, she agrees that while a happy thought, it would be unlikely. Also, Toriel and Sans already have a deep connection to the point where sans agreed not to kill humans for her sake.